We’ll now switch to using the perspective projection matrix. Open up AirHockeyRenderer and remove all of the code from onSurfaceChanged, except for the call to glViewport. Add the following code:
MatrixHelper.perspectiveM(projectionMatrix, 45, (float) width
/ (float) height, 1f, 10f);
This will create a perspective projection with a field of vision of 45 degrees. The frustum will begin at a z of -1 and will end at a z of -10.
After adding the import for MatrixHelper, go ahead and run the program. You’ll probably notice that our air hockey table has disappeared! Since we didn’t specify a z position for our table, it’s located at a z of 0 by default. ...